In a volume of air near the earth's surface, ____ occupies 78 percent and ____ nearly 21 percent.

In a volume of air near the earth's surface, ____ occupies 78 percent

1.	In a volume of air near the earth's surface, ____ occupies 78 percent and ____ nearly 21 percent.
A.	Nitrogen, oxygen
B.	Hydrogen, oxygen
C.	Oxygen, hydrogen
D.	Nitrogen, water vapor
E.	Hydrogen, helium
Answer» B. Hydrogen, oxygen